A Wide-Range Global Optimal Control Strategy for Wireless Charging Systems in Electric Vehicles

Maintaining the high efficiency of the wireless charging system for electric vehicles in the full power range is the key point and difficulty in the application. In this article, a wide-range global optimal control (WGOC) method based on the battery impedance characteristics is proposed. Compared with the existing control methods, the losses of the circuits at all levels in the wide operating range are comprehensively considered to achieve the optimization of battery charging over a wide power range. The charging demand of the battery is responded to by the current closed-loop on the secondary side, and the overall efficiency of the system is dynamically optimized by the primary side. The active rectifier implements zero voltage switching and synchronous rectification for the entire cycle. An efficiency model based on the battery load is developed to obtain the optimal curve. The steady-state parameters and the efficiency for a wide power range are accurately calculated. Finally, a 3.5 kW prototype is developed. The experimental results verify the accuracy of the parametric model. Moreover, the WGOC improves the efficiency in all power ranges and the efficiency improvement is up to 9.5% for light load. The applicability of the WGOC is also verified.